diff --git a/Lib/fontTools/varLib/__init__.py b/Lib/fontTools/varLib/__init__.py
index 22e244112..b130d5b2a 100644
--- a/Lib/fontTools/varLib/__init__.py
+++ b/Lib/fontTools/varLib/__init__.py
@@ -563,17 +563,17 @@ def _get_advance_metrics(
 ):
     vhAdvanceDeltasAndSupports = {}
     vOrigDeltasAndSupports = {}
-    # HACK: we treat width 65535 and lsb 0 as sentinel values to signal that a glyph
+    # HACK: we treat width 65535 as a sentinel value to signal that a glyph
     # from a non-default master should not participate in computing {H,V}VAR,
     # as if it were missing. Allows to variate other glyph-related data independently
     # from glyph metrics
-    sparse_metrics = (0xFFFF, 0)
+    sparse_advance = 0xFFFF
     for glyph in glyphOrder:
         vhAdvances = [
             metrics[glyph][0]
-            if glyph in metrics and metrics[glyph] != sparse_metrics
+            if glyph in metrics and metrics[glyph][0] != sparse_advance
             else None
-            for i, metrics in enumerate(advMetricses)
+            for metrics in advMetricses
         ]
         vhAdvanceDeltasAndSupports[glyph] = masterModel.getDeltasAndSupports(
             vhAdvances, round=round